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Merged
merged 2 commits into from
Dec 15, 2021
Merged

perfect_power handles all Rationals #22672

merged 2 commits into from
Dec 15, 2021

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smichr
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@smichr smichr commented Dec 14, 2021 •
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References to other Issues or PRs

Brief description of what is fixed or changed

The following used to raise a ValueError:

>>> perfect_power(0)
False
>>> perfect_power(-9)
False
>>> perfect_power(-27)
(-3, 2)
>>> perfect_power(S.Half**3)
(1/2, 3)

Other comments

Release Notes

  • ntheory
    • perfect_power now only raises a ValueError for non-Rational input

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sympy-bot commented Dec 14, 2021 •
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✅

Hi, I am the SymPy bot (v162). I'm here to help you write a release notes entry. Please read the guide on how to write release notes.

Your release notes are in good order.

Here is what the release notes will look like:

  • ntheory
    • perfect_power now only raises a ValueError for non-Rational input (#22672 by @smichr)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.10.

Click here to see the pull request description that was parsed. 
<!-- Your title above should be a short description of what
was changed. Do not include the issue number in the title. -->

#### References to other Issues or PRs
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
format, e.g. "Fixes #1234" (see
https://tinyurl.com/auto-closing for more information). Also, please
write a comment on that issue linking back to this pull request once it is
open. -->


#### Brief description of what is fixed or changed

The following used to raise a ValueError:
```python
>>> perfect_power(0)
False
>>> perfect_power(-9)
False
>>> perfect_power(-27)
(-3, 2)
>>> perfect_power(S.Half**3)
(1/2, 3)
```
#### Other comments


#### Release Notes

<!-- Write the release notes for this release below between the BEGIN and END
statements. The basic format is a bulleted list with the name of the subpackage
and the release note for this PR. For example:

* solvers
  * Added a new solver for logarithmic equations.

* functions
  * Fixed a bug with log of integers.

or if no release note(s) should be included use:

NO ENTRY

See https://github.com/sympy/sympy/wiki/Writing-Release-Notes for more
information on how to write release notes. The bot will check your release
notes automatically to see if they are formatted correctly. -->

<!-- BEGIN RELEASE NOTES -->
* ntheory
    * `perfect_power` now only raises a ValueError for non-Rational input
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

@smichr smichr changed the title do not pass silently for perfect_power(1) perfect_power handles all Rationals Dec 14, 2021
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github-actions bot commented Dec 14, 2021 •
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Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)



Significantly changed benchmark results (master vs previous release)


       before           after         ratio
     [907895ac]       [7c0fa071]
-      5.06±0.01s          376±3ms     0.07  polygon.PolygonArbitraryPoint.time_bench01
+     3.95±0.05ms      6.78±0.07ms     1.72  solve.TimeMatrixOperations.time_det(4, 2)
+     3.97±0.03ms      6.76±0.04ms     1.70  solve.TimeMatrixOperations.time_det_bareiss(4, 2)
+      45.2±0.8ms         83.5±3ms     1.85  solve.TimeMatrixSolvePyDySlow.time_linsolve(1)
+      45.6±0.8ms         84.2±1ms     1.85  solve.TimeMatrixSolvePyDySlow.time_solve(1)



Full benchmark results can be found as artifacts in GitHub Actions

(click on checks at the top of the PR).

      		
    

  





        


            

            
            

              
            

        

      


      

            
  
  

    
  
    
    

  

  

  


    












      

  
            







      

  
        

  

      

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                sympy/ntheory/factor_.py

              
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                  >>> perfect_power(Rational(1/2)**3)

            
          

          


              

              

            
                  (1/2, 3)

            
          

          


              

              

            
                  >>> perfect_power(Rational(-3/2)**3)

            
          

    








  

    

        

        

  

    

        
    
    

  


      
          
  
      
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Should this be e.g. Rational(-3, 2)?

    

  
  



    


        

      
  
  

    
  
    
    

  

  

  



          

      
    





    

        

  

    

        
    
    

  


      
          
  
      
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denominators that are powers of 2 are exactly converted...but it is better practice to do as you show


>>> Rational(1/4)
1/4

    

  
  



    


        

      
  
  

    
  
    
    

  

  

  



          

      
    








    


  









  








  








      

  
        

  

      

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        @smichr
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    December 15, 2021 17:41    
    




  

  

    
  


  

      


  This was referenced Nov 9, 2024





  


  

      

  
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